Based on the regional geological background of the South Yellow Sea Basin and the North Yellow Sea Basin, this paper describes the location and stratigraphic attribute of Line HHQY05-1 that stretches across the two basins. The authors comparatively analyzed velocity spectra, average velocity and interval velocity of the two basins, and reached the conclusion that the seismic velocities of them are quite different, and the average seismic velocity of the South Yellow Sea Basin was lower than that of the North Yellow Sea Basin, which is attributed to the differences in their geological structures, lithologic characters and geochronologic units. Therefore, the tectonic characteristics and geological attributes of the basin can be roughly detected by using the seismic velocity.